Many great businesses were started by founders aged 50+.
"The average and median age of U.S.-born tech founders was thirty-nine when they started their companies. Twice as many were older than fifty as were younger than twenty-five."
Don't worry about that. The thing you'd want to worry about, if anything, is spending years just grinding away in your one little niche.
Lots of old people start companies, but the key to success is having a wide variety of experience, and not being afraid to get more (like sales! like marketing! and so on!).
You can do it! (I did! And just landed my 4th customer for a high-dollar-value subscription service!)
I worked in 2 successful startups (successful in that it made millions for the founders) where the founders started up the business after they retired from their normal job. My experience has been that VC firms like experience. "I've got a great idea. I have contacts in the area who are lining up to join me. I have 30 years of experience running these kinds of projects. All I need is cash." is a pretty good pitch.